I have got running problems with my car (MY99) which i have had for a while, I decided to disconnect the O2 sensor and runs fine. Now I have taken the old one out to put another one in and the old one looked like this!



Should it look like this, it has been running with it Disconnected for a while.


the put the other one in, it runs a bit better but still hessitant at low revs

 

The colour looks about right, but has it got a ding or dent in the top of it?

 

I thought it should Be a grayish black, yes it is distorted, it was like it when i took it out. Could heat have caused this? or Just someone dropping it it before putting it in! Lol

 

Colour's good. It's only four inches away from the turbine don't forget - if it was sooty/black there'd be something wrong. And no that dent won't have been caused by heat alone, someone's dropped it at some point in the past.

Did you reset your ECU after fitting the alternative sensor - and is it a new one (or at least one you're confident is working 100%)?